I'm not a QGIS user but there is a similar question at gis.stackexchange.com. I'm quoting the answer from AndreJ here:
I guess you are using the QOSM plugin to display the OpenCycleMap, since the standard OSM map does not have API keys.
You can obtain an API key from the map producer Thunderforest. They provide details here, including a sample tile request URL. You can add that to the properties of the QOSM layer, inserting the line
http://a.tile.thunderforest.com/cycle/${z}/${x}/${y}.png?apikey=<insert-your-apikey-here>
and clicking on Add Custom Type. Take care of the grammar for the variables that differs from the linked site.
Alternatively, you can use the QuickMapServices plugin, which does not show an API request for that site at the moment.
answered 22 May '17, 10:53
scai ♦
33.3k●21●309●459
accept rate: 23%
The QuickMapService does so show an API request, ... and where exactly in the properties of the QOSM layer does one insert this darn API Key line?
I keep reading this in forum after forum, but there is no place in my OSM layer properties dialogue to insert such a URL line. Frustrated? You bet!! seems like a simple question to answer. I've wasted hours chasing this elusive solution. I created a thunderforest account and have the API key, now I would like to use the key to get the API request watermark off of my map display. Please, please, please in plain simple English language, could someone tell me where to apply this fiddly key in order to remove the frapping API request watermark from the background map layer?
thx.