Suztera :
Does anyone know if there is a limit with how many licenses you can "buy" from a single product from the MS Dreamspark Premium e.g. MS Visio 2013
Or is it limited to be "bought" to X number of times?
Yes there is a limit.
Most products are available in multiple versions/editions, but only a single licence is made available. For example, if you have access to Dreamspark Premium you may obtain one Windows 7 licence, one Windows 8 licence, and one Windows 8.1 licence. This was changed from a year or two ago when it was possible to obtain multiple licences for each simply by purchasing different editions. This change was necessitated by all of the morally bankrupt individuals that grabbed dozens of keys and sold them through greymarkets such as G2A