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You can also install these plugins for your own copy of Fiji, although you might not be able to run all of them efficiently if you don't have a powerful enough computer. See the following link for details of the range of update sites that can be used to update different plugins in Fiji, but bear in mind the caveat at the top of the linked page warning you about the risk of breaking your Fiji installation.
Leica LAS AF Lite and LAS X
Free browser versions of Leica's confocal microscope software have some basic processing and analysis capabilities but are probably most useful for browsing images and stacks prior to deconvolution or further processing in other software. Data from the STED will only open properly in the more recent LAS X software. LIF files from the older confocal microscopes will open in both LAS AF Lite and LAS X, but the former is probably preferable, since re-saving the data in LAS X will make the file incompatible with the machine it was acquired on.